This invention concerns apparatus for handling a plurality of articles to be loaded and unloaded with respect to a container e.g. in the automatic production of canned goods, such as canned foodstuffs. The present invention is particularly concerned with apparatus for loading and unloading cans into and from containers and particularly, but not exclusively, so-called retort baskets. These baskets act as inserts for the pressure vessels in which cans of foodstuffs are treated by steam for cooking and/or sterilizing purposes.
The operation of loading and unloading retort baskets has not previously been successfully automated and in order to ensure the orderly packing of such baskets it has been necessary to provide an attendant at the appropriate point in the automated sequence. This not only increases the cost of the process but limits the rate at which the process can be performed.
It has already been proposed to provide apparatus for stacking the cans in an orderly fashion as opposed to merely depositing them in a random fashion into the retort baskets. However, the apparatus which has been put forward to perform the packing and unpacking operations has been cumbersome and has not been entirely successful. For example, one such apparatus has utilized special retort baskets with removable bottoms. Each basket has been packed by supporting it with its bottom raised to the top of the basket on an adjustable jack and the top of the basket level with a conveyor arranged to discharge into the basket. The basket has been packed layer by layer, the bottom being lowered in one layer increments as packing proceeds and a plastics sheet been placed on top of each layer as it is completed so as to provide a surface over which the subsequent layer of cans can slide into position. Unloading has been performed by raising the bottom of the baskets layer by layer and pushing each layer of cans, as it is moved out of the basket, onto a conveyor. This apparatus only works successfully as long as the cans being discharged from the conveyor belt into the basket and, on unloading, from the basket on to the conveyor belt, do not tip over. It has, therefore, generally been necessary to provide an attendant to correct the loading/unloading in the event that cans become tipped and also to place the plastics sheets in position.
It has also been proposed that an electro-magnet be used to transfer assembled cans from an assembly station at which they are pre-positioned into the form of the basket concerned, to said basket. The same electro-magnet could, it has been proposed, be utilized to unload baskets by a reversal of this procedure. Such an arrangement has not found favour in canneries because the high moisture content of the environment results in an early failure of the insulation of electro-magnets.